The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Oregon rock-cress

Eschscholtz's hairy rock-cress, Eschscholtz's rockcress, hairy rockcress, Pacific coast rockcress

Habit Perennials; (caudex simple or branched, with some persistent petiolar remains); sparsely to moderately pubescent, trichomes bulbous-based, simple and long-stalked, forked, (to 2 mm), these often mixed with fewer 3-rayed, stalked stellate ones. Biennials or perennials; (caudex branched); usually densely hirsute (at least basally), trichomes simple or stalked, forked, sometimes glabrescent with mostly simple ones.
Stems

simple or few from base (caudex), erect, unbranched distally, (0.6–)1.7–4.5(–5) dm, (usually pubescent throughout, rarely subglabrate, coarsely hirsute, trichomes simple, mixed with forked ones).

simple or several from base (rosette), erect, often branched distally, 2–7(–10) dm, (hirsute basally, trichomes simple and minutely stalked, forked, rarely almost exclusively glabrous).

Basal leaves

petiole 0.5–2(–3) cm, (ciliate);

blade oblanceolate to obovate, (1–)2–5(–9) cm × (5–)8–18(–22) mm, margins entire or repand to dentate, (ciliate), apex obtuse, surfaces pubescent or glabrous, trichomes simple and forked, sometimes mixed with 3-rayed stellate ones.

petiole 0.7–3 cm, (ciliate or not);

blade broadly spatulate to narrowly oblanceolate, 1.2–10 cm × 7–30 mm, margins entire or dentate, apex obtuse or acute, surfaces usually pubescent, sometimes glabrous, trichomes simple, forked and stalked, stellate.

Cauline leaves

3–6 (or 7);

blade oblong, 1–3(–6) cm × 2–7(–15) mm, base not auriculate, margins entire or dentate, (ciliate or not), apex obtuse, surfaces pubescent as basal leaves or glabrous.

(2–)4–12(–18), (well-spaced or, rarely, overlapping);

blade ovate to oblong or lanceolate, 1.5–6.5(–10) cm × 5–30 mm, base auriculate, margins dentate or entire, apex acute or obtuse, surfaces sparsely hirsute or glabrous.

Racemes

simple, (dense).

simple or branched.

Flowers

sepals (purple), oblong, (5–)6–8 × 1.5–2 mm, lateral pair saccate basally;

petals purple or pink, spatulate, (10–)12–15(–16) × (3–)4–5 mm, apex obtuse;

filaments (4–)5–8 mm;

anthers narrowly oblong, 1.2–1.8 mm.

sepals oblong, 3.5–5 × 1.2–2 mm, lateral pair saccate basally;

petals white, rarely pink, linear-oblanceolate or narrowly spatulate, (5.5–) 6.5–9(–10) × 1.5–3 mm, apex obtuse;

filaments 3.5–6 mm;

anthers oblong, 0.7–1 mm.

Fruiting pedicels

ascending to erect, 5–10 mm, (pubescent or glabrous).

erect to erect-ascending, 3.5–10(–15) mm, (glabrous or sparsely pubescent).

Fruits

erect or nearly so, slightly torulose, (3–)4.5–6 cm × 1.5–2 mm;

valves each with prominent midvein;

ovules 24–30 per ovary;

style 0.5–1 mm.

erect to erect-ascending, (often appressed to rachis), torulose, 3.5–6.5 cm × 1.2–1.8(–2) mm;

valves each with prominent midvein extending full length or to middle;

ovules 54–80 per ovary;

style (0.1–)0.3–1 mm.

Seeds

narrowly winged distally or not winged, oblong, 1.8–2.2 × ca. 1 mm;

wing ca. 0.1 mm wide.

usually narrowly winged throughout or only distally, rarely not winged, oblong or suborbicular, 1–1.8 × 0.9–1.3 mm;

wing to 0.2 mm wide distally.

2n

= 32.

= 32, 64.

Arabis oregana

Arabis eschscholtziana

Phenology Flowering Apr–May. Flowering (Apr-)May–Jul.
Habitat Moist granitic soil, rocky hillsides, chaparrals, steep banks Rocky slopes, crevices, and ledges, meadows, moist banks and grounds, granitic soil, wooded slopes
Elevation 500-1000(-1400) m (1600-3300(-4600) ft) 0-2800 m (0-9200 ft)
Distribution
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CA; ID; MT; NV; OR; UT; WA; WY; AB; BC; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

Arabis oregana is known from Napa and Siskiyou counties (California) and Jackson County (Oregon).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

G. A. Mulligan (1996) recognized Arabis eschscholtziana as a distinct species; R. C. Rollins (1941, 1993) treated it as a variety of A. hirsuta. As discussed under A. pycnocarpa, A. hirsuta does not occur in North America, and the characters separating all three species (see key to species), as well as the different ploidy levels, support Mulligan’s conclusion.

Both M. Hopkins (1937) and R. C. Rollins (1941, 1993) recognized the glabrous or subglabrate forms native to North America as a distinct variety, var. glabrata; G. A. Mulligan (1996) did not accord such forms any taxonomic status. Glabrous and subglabrate forms occur in both Arabis eschscholtziana and A. pycnocarpa and sometimes even within a population that has moderately to densely pubescent forms. I support Mulligan’s view in not recognizing the glabrous forms as an infraspecific taxon.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 264. FNA vol. 7, p. 261.
Parent taxa Brassicaceae > tribe Arabideae > Arabis Brassicaceae > tribe Arabideae > Arabis
Sibling taxa
A. aculeolata, A. alpina, A. blepharophylla, A. caucasica, A. crucisetosa, A. eschscholtziana, A. furcata, A. georgiana, A. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. patens, A. pycnocarpa
A. aculeolata, A. alpina, A. blepharophylla, A. caucasica, A. crucisetosa, A. furcata, A. georgiana, A. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. oregana, A. patens, A. pycnocarpa
Synonyms A. purpurascens, A. furcata var. purpurascens A. hirsuta subsp. eschscholtziana, A. hirsuta var. eschscholtziana, A. hirsuta var. glabrata, A. ovata var. glabrata, A. pycnocarpa var. glabrata, A. rupestris, A. stelleri var. eschscholtziana, Turritis spathulata
Name authority Rollins: Rhodora 43: 349. (1941) Andrzejowski: in C. F. von Ledebour, Fl. Altaica 3: 25. (1831)
Web links